/Engine/Plugins/Online/OnlineSubsystem/Source/Public/Interfaces/OnlinePartyInterface.h
enum EJoinPartyCompletionResult { UnknownClientFailure = -100, BadBuild, InvalidAccessKey, AlreadyInLeadersJoiningList, AlreadyInLeadersPartyRoster, NoSpace, NotApproved, RequesteeNotMember, RequesteeNotLeader, NoResponse, LoggedOut, UnableToRejoin, IncompatiblePlatform, AlreadyJoiningParty, AlreadyInParty, JoinInfoInvalid, AlreadyInPartyOfSpecifiedType, MessagingFailure, GameSpecificReason, MismatchedApp, UnknownInternalFailure = 0, Succeeded = 1, }